Walk-behind lawn mowers are known having a housing supported for movement over the ground by a plurality of wheels. A single cutting blade rotates horizontally in a cutting chamber located within the housing. The user pushes or guides the mower by holding an upwardly extending handle assembly connected to the mower housing. The cutting blade cuts grass as the mower travels over the ground.
The grass clippings are often discharged through a side or rear discharge opening in the mower housing. A bagging attachment can be removably secured to the discharge opening to allow the grass clippings to be collected in the attachment. The bagging attachment can be removed from the mower housing to allow the clippings to be dumped.
Mulching mowers are known in which the usual side or rear discharge opening from the housing is absent. These "dedicated" mulchers generally have included a cutting chamber which is enclosed over the sides and top thereof and which is open only at the bottom. This allows the grass clippings cut by the blade to be deposited downwardly into the cut grass path through the open bottom of the cutting chamber. In some cases, a specially shaped blade assists in the downward movement of the grass clippings, or grass deflector members may be carried inside the cutting chamber. U.S. Pat. No. 4,205,512 to Thorud discloses a prior art "dedicated" mulcher mower utilizing grass deflector members in the cutting chamber.
Interest has grown recently in the use of mulching mowers. To that end, The Toro Company, the assignee of the present invention, has designed and introduced a line of rear discharge, walk-behind mowers that are selectively convertible by the user between grass discharging, collection, and mulching modes. The grass discharge opening is selectively blocked by an insertable plug in the grass mulching mode. In addition, these mowers include a plurality of grass deflecting members, also known as kicker members, which intercept the grass clippings circulating inside the housing to assist in their downward discharge from the cutting chamber when the mower is being used as a mulcher. One of these kicker members is located on the plug itself. U.S. Pat. Nos. 4,951,449 and 5,090,183 to Thorud illustrate such a convertible bagger/mulcher.
Many traditional mulching mowers of the kind described above are not well suited for cutting large areas of grass. Such mowers are limited in width and generally use only a single cutting blade. For example, most mowers of this type do not exceed 21 inches in width. Thus, it would be too time consuming and labor intensive to use this type of mower for cutting large areas of grass such as those found on golf courses, parks, and the like.
Mowing machines are known which are specifically designed for cutting relatively large areas of the type just mentioned. These machines include a cutting deck attached to a traction unit that is normally self-propelled for carrying the cutting deck over the ground. The cutting deck is quite wide and includes more than one blade arranged across the width of the deck to provide a wide swath of cut grass for each pass of the mowing machine.
The Toro Company has also introduced various multibladed, mulching mowers which include a plurality of blades suspended beneath a cutting deck. Each blade is contained inside a generally enclosed cutting chamber. A plurality of grass deflector members, similar to those shown in the Thorud 449 patent, are located inside each cutting chamber to assist in the downward deposition of grass when the mower is being used as a mulcher. However, this mower is not convertible to a grass discharge mode, but is a "dedicated" multi-bladed mulcher.
U.S. Pat. No. 4,226,074 to Mullet et al. discloses a multi-bladed cutting deck having a plurality of side-by-side, overlapping cutting chambers which are staggered fore-and-aft relative to one another. A single cutting blade is located in each cutting chamber. Grass is cut by the blades within each cutting chamber as the machine is driven over the ground. The grass clippings normally flow from a side cutting chamber on one side of the machine progressively through the other two cutting chambers, i.e. first through the middle cutting chamber and then through the side cutting chamber on the opposite side of the deck, to be discharged from the deck through a single side discharge outlet in the last mentioned side chamber. See FIG. 3 of Mullet et al. However, the side discharge outlet can be closed by a gate, and additional gates can be swung into closed positions between the chambers to isolate each cutting chamber from the others to prevent the flow of grass clippings between the cutting chambers. With the gates in these closed positions, the deck operates as a mulcher. See Col. 5 of Mullet et al.. Lines 49-57. There are no "kicker members" in any of the cutting chambers.
Thus, the Mullet et al. reference discloses a multi-bladed deck which is convertible between mulching and grass discharge/collection modes. Mullet discloses that a bagging attachment can be mounted on the mower to collect the grass clippings exiting from the side discharge outlet. However, in the grass discharge/collection mode, the Mullet device requires that the grass clippings flow through the interior of the cutting chambers from one side of the deck to the other to exit from the machine.
Grass clippings, particularly clippings from wet and long grass, tend to collect or stick to those cutting chamber surfaces with which they come into contact. Thus, the Mullet arrangement can result in undesirable build up of grass clippings inside the cutting chambers, i.e. in the middle cutting chamber and most especially in the second side cutting chamber having the grass discharge outlet, due to the need to pass all the clippings from all the cutting chambers through the middle and second side cutting chambers on their way to the outlet. In addition, the arrangement of cutting chambers and blade rotation directions shown in Mullet further require that the grass clippings flowing from one chamber to the next change direction quite sharply. This further exacerbates the grass clipping build up problem and detracts from the performance of the machine in its grass discharge/collection mode.